<!DOCTYPE html>
<svg>
    <filter id="dilate">
        <feMorphology operator="dilate" radius="-1"/>
    </filter>
    <rect width="100" height="100" fill="green" filter="url(#dilate)"/>

    <filter id="erode">
        <feMorphology operator="erode" radius="-1"/>
    </filter>
    <rect width="100" height="100" fill="green" filter="url(#erode)" x="100"/>
</svg>
